Laying artificial stone or concrete arches



(No Model.) P. H. JACKSON.

LAYING ARTIFICIAL STONE 0R CONCRETE ARCHES. No. 317,793. Patented May12, 1885.

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PETER H. JACKSON, OF SAN FRANCISCO, CALIFORNIA.

LAYING ARTIFICIAL STONE OR CONCRETE ARCHES.

SPECIFICATION forming part of Letters Patent No. 317,793, dated May 12,1885.

I I Applicatim filed November 2F. 1884. (X0 model.)

To all 2217110111. it may concern.-

Be it known that I, PETER H. JACKSON, of the city and county of SanFrancisco, State of California, have invented certain 'new and usefulImprovements in Laying Artificial Stone or Concrete Arches, FormingSidewalks and Floors of Buildnigs; andl declare the following to be afull, clear, and exact description thereof, sufficient to enable anyperson skilled in the art to which my invention belongs to make and usethe same, reference being had to the accompanying drawings, forming partof the specification.

Figure 1 is a perspective view of the longitudinal sectional arch. Fig.2 is a perspective View of the longitudinal sectional arch with theintermediate section divided into transverse sections. Fig. 3 is asection through Fig. 2 on the line 00 3 z.

Myinvention relates to an improved method of forming artificial stone orconcrete arches over basements, cellars,or other chambers, the topsurface forming a sidewalk or floor surface, the whole resting on ironbeams.

Plastic materials of which artificial stone or concrete arches are madeshrink, and thereby open perpendicular cracks or joints in the thinparts at the ends of the arches over thebeams or bearers which sustainthe arches. The haunches and the remaining part of the arch between thebeams being much thicker than the parts over the top of the beamsaggregate the particles in shrinking, so as to cause open these jointsare formed,the ledges over the top of the beams are weakened by thedivision and liable to crack and break off when subjected to severeusage from the following cause: The shrinkage of the material of thearch between the beams draws it away from the abutting sides of thebeams. This causes the arch to settle between the beams. To this is tobe added the settlement caused by striking the centers that is, takingaway the wooden forms upon which the arch was formed and sustained.These cause the arch to drop until the extremes reach out to meet theabutting sides of the beams, and to further settle when subjected to aload in the center of the arch. The thin ledge over the top of the beamdoes not participate in the settlement of the arch,but bears on the edgeof the top flange of the beam h at a,

Figs. land 2, which is the fulcrum, and from there to the crack or jointit is raised from the beam h, the ledge at the crack or joint being thelever which is acted on by the load passing over it to break it off ata.

The object of my invention is not to have any separation of theartificial stone or concrete over the top of the beams, and also toproduce compression of the parts.

After the beams hare set in position and the wooden centers are in placeto form the botto m of the arch, the beams are then covered and filledup to the desired height with the plastic concrete material, and on eachside up to the inclined stopping-off pieces of wood or metal, denoted bythe lines 0 d e f, Figs. 1 and 2, and the material is rammed to a properconsistency, thick paper or any other separating material usual havingbeen laid against the side of the stopping-off pieces 0 d 0 to preventthe plastic material from adhering to the remaining part of the archwhich is to be formed, or, if the plastic material is allowed to stand awhile, molders parting-sand applied or dusted on will answer thepurpose. After the stopping-off pieces have been withdrawn thisapplication will prevent sticking to the other parts of the arch to beformed. Then the mate rial is filled in between the lines 0 d and 6f, soas to form thecentral or remaining part of the arch, which is in theform of a keystone, and the sides of the arch at c d e f, first formed,are

the abutments to the keystone of the arch. ings or joints over the topof the beams. When Another mode of making the arch is to dispense withthe stopping-off pieces described, and place thick stiff paper,sheet-zinc, or other sheet metallic substance or any suitable materialthat will divide the sections and preserve the sloping lines 0 d e f,Figs. 1 and 2,

ing of wedgform will, from its own weight, as Well as any load that maycome upon it, compress itself and compress the abutments, and all partsof the artificial stone or concrete material and counteract the tendencyto separate any of the parts.

Artificial stone is Portland cement concrete, and its capacity to resistcompression is much greater than its capacity to resist separation, andby my construction all the parts are compressively employed, which isemploying the material in its strongest resisting property.

In Gen. Gilmores work entitled Ooignet Bton, or Other Artificial Stone,on page 54, is as follows: With a mixture of Portland cement one andsand two, the ratio of the crushing to the tensile strength willgenerally be found between the limits of fourteen to one and nineteen toone. With cement one and sand four it reaches as high as twenty-five toone and twenty-nine to one. With cement one and sand five as high asthirty-five to one. In the work entitled Iron Arches, by W. Airy, on theninth page, second line, referring to the voussoir arch, are thesewords, (of which my construction assimilates in as far as the forcesexerted in the material when employed As regards the strain of thematerial of the arch this will be, of course, a simply compressedstrain, distributed more or less ac cording to the degree of elasticitywhich exists in the stone. 0n the twelfthline are these words: In caseof the continuous arch, it must be understood there is at every point abending moment and a thrust force. Therefore,an arch made in one pieceextending from beam to beam when employed, the lower part extending downto the intrados is subjected to separation of the parts of whichconcrete is so feeble to resist. In addition to this the shrinkage ofthe plastic material when the moisture is drying out draws away from thesides of the beams against which they abut; hence the arch must stretchout when employed to meet the abutting sides of the beams which it hasdrawn away from in shrinkage.

All concretes have much greater capacity to resist compression thanseparation. By this means of greatly strengthening the arches I amenabled to make them of less thickness and of equal strength to thosemade in one piece between the beams; also there is a saving in the costof the sustaining-beams as they have to carry less weight than if thickand heavier arches were used.

Another feature of my invention, as shown in Figs. 2 and 3, is in makingthe arches cut through on an incline or taper prepared in a crossdirection to those described, so that they may be lifted out withoutdisturbing the side sections B, as in case of the breaking of any of thesections, instanced by the falling of the I front of the building on itin case of fire.

Section 9, Figs. 2 and 8 may be lifted out without disturbing sections 6t or the beamsections B B; or sections i and i can be lifted out withoutdisturbing the longitudinal beamsections B B.

At the place of the divisions of the sections, should it be necessary toprovide against leakage, thin strips of wood or metal may be set forminga channel between the sections either on the top orbottom surface, andwhen the material has become set and hard the strips are withdrawn andthe channels are filled up with plastic or other cement.

Having thus described my invention, what I claim as new, and desire tosecure by -Letters Patent, is V v 1. A sidewalk or floor consisting ofartificial stone or concrete longitudinal sectional arches, the sidesections of the arches formed in a plastic state on the sides and overthe top of the supporting-beams and supporting an intermediate separatedsection, substantially as herein described.

2. A sidewalk or floor consisting of artificial stone or concretelongitudinal sectional arches, the side sections of the arches formed ina plastic state on the sides of the supportingbeams and supporting anintermediate separated section which produces compression, substantiallyas herein described.

3. A sidewalk or floor consisting of artificial stone or'c-oncretelongitudinal sectional arches, the side sections of the arches formed ina plastic state on the sides and over the top of the supporting-beamsand with sloping sides which support a separated intermediate section,also with sloping sides conforming to the sides of the side sections,substantially as herein described.

4. Asidewalk or floor consisting of artificial stone or concretelongitudinal sectional arches, the side sections formed in a plasticstate on the supporting-beams and with sloping sides faced with sheetmetal, thick paper, or other separating material which will permit theintermediate section formed on it to wedge and produce compression ofthe parts, substantially as herein described.

5. A sidewalk or floor consisting of artificial stone or concretelongitudinal sectional arches, the side sections of the arches formed ina plastic state on the sides of the supporting-beams and supporting aseparate intermediate section, the intermediate section divided intotransverse sections with sloping supportingedges, so that the pieces maybe lifted out without disturbing the side sections, substan tially asherein described.

6. In a sidewalk or floor consisting of artificial stone or concretelongitudinal sectional arches, the side sections of the arch formed in'a plastic state on the supporting-beams, and supporting a separatedintermediate section with channels between the sections on eithersurface filled with plastic or other cement, substantially as hereindescribed.

PETER H. JACKSON.

Witnesses:

LINCOLN SAMTAG, JAMES B. LANE.

